1. Field of the Invention
This invention relates to product packaging, and in particular, it relates to packaging for products suitable for store merchandising.
2. Description of the Related Art
A first type of conventional packaging for consumer products, shown in FIGS. 6(a) and 6(b) (which is a cross-sectional view along the direction of arrows 2-2), is made of two sheets of corrugated cardboard 101 and 102, and a clear plastic container 103 having a flat insertion portion 103a and a chamber portion 103b. The insertion portion is sandwiched between the two cardboard sheets 101 and 102, and the chamber portion 103b protrudes from the plane of the cardboard sheets via a cut (opening) on one cardboard sheet 101 and is used to hold the product inside. A second plastic container 103′ may be provided and protrudes from the other cardboard sheet 102 to form a continuous space for hold the product. The two cardboard sheets 101 and 102 are adhered together around the periphery with an adhesive 104. A commonly used adhesive is a hot melt glue. The front and back sides of the package are typically printed with product information and other information. (In these drawings, the spaces between the various layers are exaggerated to illustrate the relationship among the various layers.) One disadvantage of this type of conventional packaging is that the hot melt glue is typically applied by hand, and thus the seal quality is often difficult to control due to, for example, the varying drying speed of the glue, the placement of the glue, etc. Another disadvantage is that the corrugation of the cardboard is visible at some of the side edges of the finished packaging (see FIG. 6(c), a view of the bottom edge of the packaging of FIG. 6(a)), making the packaging aesthetically unappealing.
A second type of conventional packaging, shown in FIG. 7(a), is similar to the first type shown in FIGS. 6(a)-(c), but uses one sheet of corrugated cardboard 112 (typically the back sheet) and one flat sheet of paper 111 (typically the front sheet, i.e., on the side of the product chamber). Sometimes two flat sheets of paper 111 and 111′ are used, one on each side of the corrugated cardboard (see FIG. 7(b). The cardboard sheet 112 and the flat paper sheet 111 are adhered together by a heat-sensitive adhesive 114 to seal the package. The heat sensitive adhesive is pre-applied to the cardboard sheet and/or the flat paper sheet, and heat is applied from the paper side, conducted to the adhesive via the paper to activate the adhesive. Heat sensitive adhesives have not been used in the first type of packaging because corrugated cardboard sheets are poor heat conductors, and heat applied to the outer side of the cardboard cannot easily reach the area between the two cardboard sheets where the heat adhesive material would be applied.
A disadvantage of the second type of conventional packaging is that it sometimes lacks sufficient structural strength. Display packs are often transported in an assembly where a plurality of display packs are stood on their sides in a container with half-height walls (i.e. walls not as high as the packs themselves), and wrapped together to form a box-shaped bundle. When two or more of such bundles are stacked on top of each other, the weight of the top one is supported directly by the packs in the bottom bundle. The packs therefore must have sufficient structural strength and rigidity to prevent them from bending. The lack of physical strength also makes it difficult to make larger packages (e.g. larger than 10 by 15 inches), or to pack heavier items.